Medium Duty Operator's Manual - Peterbilt Motors Company
Medium Duty Operator's Manual - Peterbilt Motors Company
Medium Duty Operator's Manual - Peterbilt Motors Company
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Preventive Maintenance<br />
• During wheel balancing, dyno testing, or any time the<br />
ignition is on with part of the ABS disconnected, a failure<br />
code will be recorded. Consult with your <strong>Peterbilt</strong> Dealer<br />
or Authorized Service Center for information on clearing<br />
the failure code.<br />
If, due to operating conditions, a brake application causes<br />
either wheel on the same axle to begin skidding, wheel<br />
speed sensors immediately signal the anti-lock controller in<br />
the modulator assembly. The controller responds instantly by<br />
signaling the solenoids in the modulator which activate the air<br />
valves, reducing application pressure as needed to prevent<br />
the wheels from locking up. If this over-riding correction is<br />
effective, application pressure is allowed to build up to the<br />
original input.<br />
Any malfunction of the anti-lock system on one or more axles<br />
will cause the system to fail-safe, and the panel-mounted<br />
amber warning light will come on, indicating both a malfunction,<br />
and automatic shut-down of the system. If the foundation<br />
brake system is intact, the service brakes will continue to<br />
function normally, but without benefit of the anti-lock feature.<br />
Brake System<br />
NOTE: If one wheel on any driven axle continues to<br />
slip or spin for approximately 4 seconds, this will<br />
cause the anti-lock controller for that axle to go into<br />
the fail-safe mode, and the warning light will give a<br />
shutdown signal.<br />
•In this case, the anti-lock system can be turned<br />
back on, and the warning light extinguished, by turning<br />
the key switch OFF and ON, after the vehicle has<br />
been brought to a full stop. When the key switch is<br />
turned back on, the warning light will illuminate and<br />
remain on for 3 to 5 seconds. This is a built-in function<br />
test of the warning light.<br />
WARNING! Do not attempt to recycle the antilock<br />
system by turning the keyswitch OFF and<br />
ON until the vehicle has been brought to a full<br />
stop and the parking brakes set. Failure to do so<br />
could adversely affect steering and braking control,<br />
and may result in loss of vehicle control and<br />
an injury accident.<br />
<strong>Medium</strong> <strong>Duty</strong> (R05/09) Y53-6008A – 189 –
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